(1) Field of the Invention
The present invention relates to a vinyl chloride polymer resin composition having incorporated therein, as a processing aid, a specific polymer prepared by a sequential three-stage polymerization process and having a good dispersibility in a vinyl chloride polymer resin.
(2) Description of the Related Art
Since a vinyl chloride polymer resin has excellent physical and chemical properties, the resin is widely used for the production of rigid articles such as films, sheets and bottles, and non-rigid articles such as floor covering materials and wire coverings. However, the vinyl chloride polymer resin has poor processability.
As means for improving the poor processability of the vinyl chloride polymer resin, Japanese Examined Patent Publications No. 52-1745 and No. 52-1746 have proposed a vinyl chloride polymer resin composition comprising a vinyl chloride polymer resin and, incorporated therein as a processing aid, a polymer obtained by a sequential two-stage polymerization process wherein a predominant amount of a copolymer component (A) comprising a predominant amount of a methyl methacrylate and a minor amount of an alkyl acrylate, and a minor amount of a polymethyl methacrylate component (B) are prepared either in the order of components (A) and (B) or in the order of components (B) and (A).
The above-proposed vinyl chloride polymer resin composition has excellent processability because the gelation of the vinyl chloride polymer resin is promoted without degradation of the good characteristics possessed by the resin, and a molded article prepared from this resin composition exhibits excellent surface condition, transparency, and secondary processability. However, this resin composition has a problem in that blocks are readily formed at the blending step before the processing, especially during the mixing in a Henschel mixer, and difficulties such as adhesion to the vessel wall occur at the blending step.